DWM1001 odd TLV command response

Hi there, i’m using the MDEK1001-DevBoards with the given uart interface and the tlv command set.
During the initialization of the modules i got some odd response behaviour of the DWM1001 module.
Within the initialization sequence i got some undocumented responses like 0xFF( one single byte ) or 0x40 0xE1 ( two bytes). The DWM1001 responses to the most commands correct with the generic response 0x40 0x01 0x00.
The first occur of the odd response is at the DWM_Tag_Cfg_Set command. In my case is send 0x05 0x02 0x32 0x04 and the response is 0xFF after 438ms.
The second occur of the odd response is at the DWM_Tag_Panid_Set command. In my case is send 0x2e 0x02 0xFE 0xAF and the response ist 0x40 0xe1 after 75ms.

I guess the commands are valid, but the received repsonse, i got from DWM1001, is not documented in the firmware API guide.
May someone can help me in here?
Best regards